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S Andrews

Publications and source records attributed to S Andrews.

At least 55 records · Page 3Linked to original sources
PubMed1995

An EP receptor with a novel pharmacological profile in the T-cell line Jurkat.

1. Comparison of the rank order of potency of the natural prostanoids prostaglandin E2 (PGE2), PGD2, PGF2 alpha and carbaprostacyclin in stimulating cyclic AMP in Jurkat cells is consistent with the presence of an EP receptor. 2. Lack of responsiveness to the EP1/EP3 selective agonist, sulprostone, and the EP2 agonists, butaprost and AH 13205, indicates that this receptor is not of the EP1, EP2 or EP3 subtypes. 3. Inhibition of PGE2-stimulated cyclic AMP by the EP4 antagonist, AH 23848 is non-competitive, unlike the competitive antagonism reported in the pig saphenous vein EP4 preparation. Furthermore, 16,16-dimethyl PGE2 is 100 fold less potent than PGE2 in Jurkat cells, while these agonists are equipotent in the rabbit jugular vein purported EP4 preparation. In addition, 1-OH PGE1, which also is active in the rabbit jugular vein preparation, is inactive in Jurkat cells at concentrations up to 1 x 10(-4) M. These data are not wholly consistent with any adenylate cyclase coupled EP receptor described to date. 4. It is postulated that an EP receptor, positively coupled to adenylate cyclase, with a unique pharmacological profile is present in Jurkat cells.

Adenylyl Cyclases↗
PubMed1995

Brain potential evidence for an auditory sensory memory deficit in schizophrenia.

OBJECTIVE: The multiple disorders of selective attention found in schizophrenia could be secondary to disturbances in sensory processing. The authors investigated this possibility by using an event-related potential index of auditory sensory memory, called "mismatch negativity." METHOD: Medicated (N = 11) and neuroleptic-free (N = 11) patients with schizophrenia and patients with bipolar affective disorder (N = 11) were compared with age- and sex-matched healthy comparison subjects. Auditory stimuli were presented while the subjects were distracted with an attention-demanding visual task. Event-related potentials were elicited by infrequently occurring auditory stimuli (deviants) and by regularly presented auditory stimuli (standards), which differed slightly in duration. The difference in amplitude between the event-related potentials elicited by the deviant and standard stimuli was the mismatch negativity. RESULTS: The amplitude of the mismatch negativity was significantly lower in both groups of schizophrenic patients than in the healthy comparison subjects. Mismatch negativity amplitude was significantly correlated with ratings of negative schizophrenic symptoms but not with positive symptoms. Compared with the matched comparison subjects, the bipolar affective disorder patients did not show lower amplitude of mismatch negativity. There was a significant negative correlation between age and mismatch negativity amplitude. CONCLUSIONS: The abnormal auditory sensory memory processing indicated by low mismatch negativity amplitude in the schizophrenic patients cannot be accounted for by neuroleptic medication status. Because this abnormality was significantly related to measures of negative symptoms only, it may be a chronicity marker or reflect a predisposition to the development to schizophrenia. These findings implicate the auditory cortex in the pathophysiology of schizophrenia.

Acoustic Stimulation↗
PubMed1995

Instance-based categorization: automatic versus intentional forms of retrieval.

Two experiments are reported which attempt to disentangle the relative contribution of intentional and automatic forms of retrieval to instance-based categorization. A financial decision-making task was used in which subjects had to decide whether a bank would approve loans for a series of applicants. Experiment 1 found that categorization was sensitive to instance-specific knowledge, even when subjects had practiced using a simple rule. L. L. Jacoby's (1991) process-dissociation procedure was adapted for use in Experiment 2 to infer the relative contribution of intentional and automatic retrieval processes to categorization decisions. The results provided (1) strong evidence that intentional retrieval processes influence categorization, and (2) some preliminary evidence suggesting that automatic retrieval processes may also contribute to categorization decisions.

Adult↗
PubMed1995

Pain responses of hospitalized neonates to venipuncture.

Neonates' response to pain after venipuncture was studied by observing, recording, and measuring physiological and behavioral responses. The measurement used was the National Individualized Developmental Care Assessment Program (NIDCAP). Data were recorded from a convenience sample of 30 neonates required to have a venipuncture as part of their routine treatment for 20 minutes before and 20 minutes following the procedure by a person certified as reliable in administering the NIDCAP. Both behavioral and physiologic changes were observed. Most of the infants (93 percent) moved abruptly into a hyperalert or crying state in response to venipuncture, skipping several states without transition and showing disorganized behavior. The heart rate, oxygen saturation, and skin color showed significant changes when data recorded just prior to venipuncture were compared to data recorded immediately following the procedure. Nursing implications, including the unit environmental elements, are discussed.

Bloodletting↗
PubMed1994

Complete nucleotide sequence of Saccharomyces cerevisiae chromosome VIII.

The complete nucleotide sequence of Saccharomyces cerevisiae chromosome VIII reveals that it contains 269 predicted or known genes (300 base pairs or larger). Fifty-nine of these genes (22 percent) were previously identified. Of the 210 novel genes, 65 are predicted to encode proteins that are similar to other proteins of known or predicted function. Sixteen genes appear to be relatively recently duplicated. On average, there is one gene approximately every 2 kilobases. Although the coding density and base composition across the chromosome are not uniform, no regular pattern of variation is apparent.

Base Composition↗
PubMed1993

Event-related potential indices of semantic processing in schizophrenia.

Event-related potentials (ERPs) were recorded while schizophrenic patients and healthy controls read congruous and incongruous sentences in anticipation of a memory test. The schizophrenic group performed more poorly in both recognition memory and cued recall tests. The two groups did not differ in the amplitude of the N400 component of the ERP but the difference between the ERPs to congruous and incongruous sentences persisted longer in the schizophrenic sample. The schizophrenic sample also showed reduced parietal positivity and a reduced effect of congruity on the late positive component that follows N400. Within the schizophrenic sample, measures of attentional impairment and positive thought disorder were correlated with mean amplitude of both the N400 and the subsequent positivity. The results imply that the structure and spread of activation within semantic memory is not impaired in schizophrenia. Rather, impairments appear to lie in processes required to integrate activated information with the current context.

Adolescent↗
PubMed1993

Feature-based versus exemplar-based strategies in preschoolers' category learning.

Five experiments examined whether preschool children learn categories by formulating a categorization rule based on attention to one or two features, or by memorizing the category assignment for whole exemplars. Using fictitious animals as stimuli, children were taught a two-category discrimination at the basic level and were tested for their category learning using a procedure that required them to categorize from memory, rather than perform perceptual matching. Transfer stimuli manipulated the retention of features encountered in the training instances, and children were instructed to classify only the items about whose category membership they were certain. By measuring the extent of generalization, in addition to categorization accuracy, it was possible to assess whether children were applying a feature-based rule in making their categorization decisions. The studies found little evidence that children were employing rules. Analyses of the individual response patterns identified few children who categorized by attending to a single attribute such as shape, or else who used a two-feature disjunctive rule. In addition, a recognition memory test given after category gaining produced strong evidence that children had encoded the training examples as wholes, rather than focusing on individual features. Despite clear evidence that children had encoded the training examples, however, examplar information was not used successfully in categorization when subjects were trained on only a single instance per category. The implication of these results for theories of early categorization are discussed.

Attention↗
PubMed1993

Event-related potentials and repetition priming in young, middle-aged and elderly normal subjects.

Although the structure of semantic memory appears to be unaffected with increasing age, there is evidence that older adults are less efficient at accessing stored memory representations. Aging also results in a decline in the ability to use contextual information effectively, suggesting a deficit in episodic memory processes. The present experiment examines the effects of age on memory retrieval of stored representations and the use of contextual information. Event-related potentials (ERP) were recorded to immediate and delayed word repetition during a lexical decision task. Three groups of subjects were tested: young (mean = 27.3 years), middle (mean = 46.7 years) and old (mean = 67.4 years). Behavioral facilitation due to repetition did not significantly differ across groups. With increasing age, the ERP waveform showed a positive shift which began around 300-400 ms post-stimulus and was apparent across all stimulus types and response conditions. This positive shift may reflect an age-related decrease in cortical excitation. Although the onset of the ERP repetition effect was not affected by age, its duration for both immediate and delayed repetition was significantly prolonged. In the light of recent models of ERP word repetition effects, these results suggest that processes related to accessing stored representations in memory are unaffected by age. The extended duration of the repetition effect and the increase in the magnitude of the effect of delayed repetition with age suggest that aging affects processes related to the retrieval and use of contextual information in integrating a stimulus with its context.

Adult↗
PubMed1993

An event-related potential study of semantic congruity and repetition in a sentence-reading task: effects of context change.

This experiment examined the joint effects of semantic congruity and repetition on event-related brain potentials (ERPs) elicited in a sentence priming task. In an initial training phase, subjects were familiarized with a list of 60 congruous and incongruous sentences. During the second phase, ERPs were recorded as subjects silently read a set of 180 unconnected sentences. One third of the sentences were presented exactly as they had been seen in training (Old sentences), one third were presented for the first time (Completely New sentences), and one third involved a re-pairing of the frames and completions of the congruous and incongruous Old sentences (New Pair sentences). The N400 congruity effect was reduced for Old as compared with Completely New and New Pair sentence completions. These results suggest that N400 reflects processes that are sensitive to both existing semantic associations and representations of previous episodes that include the context of the eliciting stimulus. A late positive component (LPC) involving a sustained positive shift in the waveform after 600 ms was largest for incongruous completions and occurred somewhat earlier for Old sentences. This pattern of results is consistent with the notion that the LPC is an index of episodic retrieval and elaborative processes. The data also suggest the presence of an early onset slow positive shift that is only evident for New Pair congruous sentences.

Adolescent↗
PubMed1993

The mother-child relationship in the HIV-1 positive family.

Qualitative data (N = 80) from a larger study of HIV-1 positive mothers have revealed mother-child relationships, that is, a strong attachment along with a bond of secrecy. The relationship is described as a strong attachment along with a bond of secrecy. Children are perceived by the mothers as sources of support as well as sources of stress in the relationship. We conclude that practice and policy decisions concerning HIV-1 positive mothers should include emphasis on maintaining the health of the mother-child dyad, providing respite to mothers and providing support for future planning.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Pelvic schwannoma in pregnancy. A case report.

Schwannomas are benign nerve sheath tumors that may originate at any anatomic site. Usually they are found on the peripheral nerves of the head, neck or flexor surfaces of the upper extremities. Rarely does a schwannoma originate in the pelvis and present as a retroperitoneal pelvic mass. Only two previous cases of a pelvic schwannoma complicating pregnancy have been presented in the English-language literature. We present a third case.

Adult↗
PubMed1992

Growth of a leiomyosarcoma of the inferior vena cava.

Until recently, leiomyosarcoma of the inferior vena cava was rarely diagnosed preoperatively. The authors describe a patient who was treated for 12 months on the basis of a presumptive diagnosis of thrombosis of the inferior vena cava. Abdominal ultrasonography and computed tomography demonstrated interval growth, and venous biopsy revealed a malignant spindle-cell neoplasm. Surgical excision confirmed the presence of a leiomyosarcoma, which had grown slowly for at least several months before entering a phase of accelerated growth.

Adult↗
PubMed1991

Anaesthesia for caesarean section in a patient with acute fatty liver of pregnancy.

A 23-yr-old woman presented in labour and hepatic failure. The clinical diagnosis was acute fatty liver of pregnancy. A Caesarean section was performed under epidural anaesthesia, after correction of a coagulopathy. Epidural anaesthesia was chosen because of the potential deleterious effects of general anaesthesia on liver blood flow and function.

Adult↗
PubMed1991

The effect of repeated testing on ERP components during auditory selective attention.

The present study examined long-term repetition effects on human auditory event-related potentials (ERPs). ERPs were recorded from subjects performing the same multidimensional auditory selective attention task on six separate occasions spaced one week apart. The task required subjects to attend to tones that varied along the dimensions of location (L), pitch (P), and duration (D) and to detect prespecified target (L + P + D +) combinations of these attributes. Processing negativity (PN) between 100-400 ms did not change in amplitude or onset latency as a function of repeated experience with the task. In contrast, two measures of "very late" PN were reduced with practice. Specifically, the location effect measured over the 400-700-ms epoch was significant only for Weeks 1 and 2, and the separation of the L + P + D- ERP from other D- ERPs, measured over the 700-1000-ms epoch, was significantly reduced from Week 1 to Week 2. A late negative component (700-1000 ms) elicited by correctly identified targets increased between Weeks 1 and 2, consistent with subjects adopting the strategy of rehearsal of the target itself rather than the L + P + D- standard. P2 amplitude increased significantly for all standards, possibly due to decreased latency jitter in later weeks. N1 latency became significantly shorter over weeks, reflecting either increasing confidence in stimulus discrimination with repeated testing or the overlapping of an unchanging N1 with an increasing P2.

Acoustic Stimulation↗
PubMed1991

Effects of inter-item lag on word repetition: an event-related potential study.

Prior exposure to a word can greatly facilitate performance to subsequent presentations of that word. ERP studies have shown that this facilitation is associated with an attenuation of a negative peak normally occurring around 400 ms poststimulus. Recent studies have interpreted this repetition effect as reflecting either lexical access or episodic memory mechanisms. However, there is now increasing evidence that neither of the above mechanisms alone can fully account for repetition effects. The present experiment recorded ERPs to immediate and delayed word repetition during a lexical decision task in order to investigate the time-course of ERP repetition effects. Immediate repetition was found to produce greater response facilitation than delayed repetition. The ERP waveforms of both immediate and delayed word repetition diverged from that of initial word presentation at approximately 300 ms poststimulus. The waveforms for repeated words separated around 400 ms poststimulus with immediate repetition showing a more rapid resolution of negativity and earlier late positivity than delayed repetition. It is suggested that the negativity may reflect processes involved in the overall activation contributing to word recognition, whereas the late positivity may be related to the repetition of stimulus categorization and decision processes.

Adult↗